Total knee arthroplasty (“TKA”) and partial knee arthroplasty (“PKA”) are common procedures for treating knee pain associated with different maladies. In both TKA and PKA, the joint surfaces of the tibia and femur are resurfaced to receive joint prostheses through a series of resections that remove carefully measured portions of bone. While many different techniques may be utilized during such surgeries, instruments are often provided for ensuring the necessary resections are made to allow for the proper alignment of implanted prostheses. For instance, the distal femur may be measured utilizing various instruments in order to help determine the optimal prosthesis size for the particular patient and to help determine the amount of bone to be removed.
One such instrument is referred to as an anterior/posterior (“A/P”) sizer, an example of which is shown in U.S. Pat. No. 6,013,081, and is typically utilized to measure the distance between the anterior cortex of the femur and the most prominent aspect of the posterior femoral condyle(s). Current A/P sizers have a pair of feet (or a foot when performing a PKA) that are inserted through an incision in the patient's soft tissue and placed in contact with the most prominent aspect of the posterior condyles. Ensuring contact with the posterior condylar prominences, which as used herein means the most posteriorly prominent point of the posterior condyles, is important as failure to reference these landmarks can affect the final positioning and sizing of the femoral prosthesis.
Current A/P sizers are constructed to be universal to the right and left legs of the entire population of patients. Such devices are also provided with feet that have long broad reference surfaces in order to ensure contact with the posterior condylar prominences, the precise locations of which are generally unknown, and account for variances in the locations of these prominences between each patient and each leg. However, such feet are exceedingly large and difficult, if not outright impossible, to utilize in a minimally invasive TKA or PKA. In other words, the sheer size of the feet of existing A/P sizers often require a large incision and extensive arthrotomy to allow the feet to access the posterior condyles, which may complicate patient recovery and increase recovery time.
Therefore, there exists a need for an improved femoral sizer instrument for use in TKA and/or PKA procedures.